Case A. (Verminous pneumonia (Ascaris sum))
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History
Grain fed calves, 200-250 kg, with onset of respiratory signs.
Example histopathological description
In this section of lung, the bronchioles and alveoli contain macrophages, neutrophils, lymphocytes, plasma cells and eosinophils, admixed with oedema and fibrin, haemorrhage, karyorrhectic debris, and cross and tangential sections of larval nematodes of 40-65 µm diameter. The nematodes have a thin cuticle, coelomyarian musculature, large lateral cords and alae, a pseudocoelom filled by the lateral cords and an intestine of uninucleated cells. Bronchiolar epithelium is multifocally hyperplastic and there is atelectasis and emphysema with mild pneumocyte hyperplasia. Multifocally, there is expansion of interlobular septae with similar inflammatory cells plus oedema and dilation of lymphatics, some of which contain macrophages, eosinophils, neutrophils and multinucleate giant cells.
Morphological diagnosis
Pneumonia, broncho-interstitial, eosinophilic, subacute, diffuse, severe, with larval nematodes
Aetiological diagnosis
Verminous pneumonia associated with Ascaris suum larvae.
Case B. (Actinobacillosis)
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History
An overdue foal, born weak, became comatose and died at 2 days of age.
Example histopathological description
This kidney section is a single wedge extending from the papilla to the capsule. Within the cortex and extending into the medulla there are numerous randomly scattered, variably sized (up to 2 mm diameter) aggregates of degenerate and viable neutrophils, lymphocytes and macrophages that surround abundant basophilic granular material (coccobacilli) and necrotic debris. These foci are often centred on glomeruli with approximately 50% of the glomeruli affected. The extent of glomerular involvement ranges from thrombosis of glomerular capillaries and distension of the vessel lumen by a myriad of coccobacilli, to obliteration of the normal glomerular structure and extension of intense neutrophilic infiltration to the adjacent interstitium and tubules. Affected tubules are often lined by epithelial cells with pyknotic nuclei, or have sloughed epithelial cells within the lumen, and many are distended by large colonies of coccobacilli. Occasional scattered arterioles show separation and dark eosinophilic staining of the smooth muscle cells within the tunica media, and the endothelium of the tunica intima is disordered. At one margin of the section the renal capsule is expanded by oedema and focally infiltrated by small numbers of mononuclear cells that have also infiltrated the adjacent peri-renal adipose tissue. There is moderate multifocal interstitial congestion and haemorrhage within the cortex.
Morphological diagnosis
Glomerulonephritis, embolic, suppurative, acute, multi-focal, severe, with intralesional coccobacilli.
Suggested aetiology
Actinobacillus equuli